I'm just curious. As I spend a minimum of three hours on each picture.

Something like these:

So far I've been tipped 450k, 100k, and 100k respectively. 

But I'm kind of eh about what I've recieved for them.

I'd like to have some second opinions.

I think 300+ is decent. They're lovely and sketchy so I think around 3-500 are reasonable prices, but of course it's also about how the ARTIST feels about his/her work. I myself have a hard time pricing my work. This year though my parents kind of got angry with me for selling my art for the prices they were at. (Example: I sold an oil painting for 50, and a few days later someone saw a cell phone picture of it that my dad had and said he'd pay 1k for it...but it was gone already....)

It's hard to know how to price one's work. It really is. I think over years of practice and experience though, you soon figure out. Though, being that this is a virtual pet site, and it would be simple, mostly no-fuss commissions, I'd say that price is fine. xP

You COULD hold price auctions too, to see how far you can get or see how far people will dive into their tu for your talent. I have found that expiramenting helps ;P